The gradient of the AOT40f values is similar to those of the AOT40c for crops: relative low in northern Europe, and the highest values observed in the countries around the Mediterranean.
The critical level is met in north Scandinavia, Ireland, part of the UK and in the coastal regions of the Netherlands (total forested area with concentrations below the critical level is 22 % of a total area of 1.44 million km2). In south Europe levels may be as high as 4-5 times above the critical level.